Time and change 1 (fossils, types and preservation potential)

Lithofacies

Include all the physical and chemical characteristics of a rock

Biofacies

rocks deposited under similar depositional conditions as determined by fossil content

Body fossils

Hard parts of whole or fragmented organisms

Body fossil examples

Shells, bones, teeth

Trace fossils

Indicates that an animal or plant was there

Trace fossil examples

footprint, trail, burrow

Original composition

Soft body, low pp
Hard body, high pp

Energy levels

High energy, more transport and erosion, low pp
Low energy, animals settle on the sea bed, high pp

Transport distance

High transport, smaller fossil, higher pp

Rapidity of burial

Fast burial, high pp
Slow burial, low pp

Amount of oxygen

High oxygen, low pp
Low oxygen, high pp

Size of sediment

Fine, high energy, low pp
Coarse, low energy, high pp

Diagenesis

Compaction, cementation, lithification, high pp
metamorphism, destroys fossil, low pp

Scavengers

Eat and destroy remains, low pp

Weathering and erosion

High rate, low pp
Low rate, high pp

Life assemblage

A group of fossils preserved together in one location

Death assemblage

Transported to another area so fossils are broken

Replacement preservation

The complete removal of original hard parts by solution and deposition of a new mineral in its place

Silicification

The fossil is dissolved and replaced by silica dioxide creating a mold

Pyritisation

Replacement of original material by iron pyrites in anaerobic conditions

Carbonisation

An increase in Carbon leads to the creation of a carbon film which preserves organisms in shales and mudstones

Exceptional preservation

A type of fossilisation of an unusually high quality or abundance

Mold

A type of fossil formed when a shell or other hard part of an organism dissolves, leaving an empty space in the shape of the part.

Cast

A type of fossil that forms when a mold becomes filled in with minerals that then harden

Nektonic

Swimmers

Planktonic

Free floating

Pelagic

Open water

Benthonicc

Lives on or in the sea floor

Epifaunal

Living on or attached to the seafloor

Infaunal

Living within the sea floor

Sessile

An organism that remains attached to a surface and does not move

Brachiopods

One shell bigger than the other, line of symmetry down the shell

Bivalves

Both shells the same size, line of symmetry between shells

Graptolites

A colony of tiny invertebrates